Firo's faith in Luna's children skills is greater than her own, but it's a nice sentiment even if she doesn't have confidence in it. "Thank you, but I don't think it's any fault of my creator or his son, that my mission wasn't successful. It's just what I am." Luna knows Firo won't agree, but at the same time it's what she believes. She's never known any other possibility.

And to be fair, it's not really fair to blame Sigma for this particular issue. He couldn't have known what would happen. "Actually, my creator was as surprised as I was when things didn't go as planned. It was his son who made the final decisions, though. He was six years old then, old enough to know what he wanted out of a mother. And that...wasn't me."